Downhole operations often include a downhole string that extends from an uphole system into a formation. The uphole system may include a platform, pumps, and other systems that support drilling operations, resource exploration, development, and extraction. In some instances, fluids may be passed from the uphole system into the formation through the downhole string. In other instances, fluid may pass from the formation through the downhole string to the uphole system. The downhole string may include various sensors that detect downhole parameters including formation parameters and parameters associated with the downhole string.
It is desirable to communicate information from downhole sensors to the uphole system. Communication may take place through wired, optical, or acoustical systems. Acoustical systems rely upon passage of pressure pulses generated downhole by a mud pulser to an uphole receiver. The pressure pulses are created by moving a piston into a choke valve in order to create an additional temporarily pressure increase at the pump system on the surface. The generated pressure pulse travels to the surface. The uphole receiver converts the pressure pulses to data indicative of sensed parameters. The pressure pulses provide useful information to uphole operators.
During drilling, a typical mud pulser substantially continuously generates pressure pulses over long time periods, often several days. In addition, a number of wellbores are currently drilled in formations having temperatures that are above 300° F. (149° C.). A majority of currently utilized mud pulsers include oil fillings, elastomers and/or electrical high pressure connectors, all of which tend to deteriorate over time and thus are not suitable for use in high temperature environments. The disclosure herein provides pulsers that are suitable for high temperature environments while also being made without oil fillings, elastomers or electrical high pressure connectors.